El Niño
Introduction
El Niño is a climate pattern characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Niña, which is characterized by unusually cold ocean temperatures in the Equatorial Pacific. El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.
Background
The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. The name El Niño was used by fishermen off the coast of Ecuador and Peru to refer to the warm ocean current that usually appears around Christmas and lasts for several months. Fish are less abundant during these warm intervals, so fishermen often take a break to repair their equipment and spend time with their families. In Spanish, the capitalized term "El Niño" means "The Boy", so named because the pool of warm water tends to appear around Christmas.
Causes
El Niño results from interaction between the surface layers of the ocean and the overlying atmosphere in the tropical Pacific. It is the internal dynamics of the coupled ocean-atmosphere system that determine the onset and termination of El Niño events. The physical processes are complicated, but they involve feedbacks between the atmosphere and ocean. In normal, non-El Niño conditions, the trade winds blow towards the west across the tropical Pacific. These winds pile up warm surface water in the west Pacific, so that the sea surface is about half a meter higher at Indonesia than at Ecuador.
Effects
El Niño has significant economic and social impacts. It can influence global atmospheric circulation, thereby affecting temperature and precipitation across the globe. It can lead to intense storms in some places and droughts in others. Temperature and rainfall anomalies during El Niño and La Niña are generally opposite in sign. For example, parts of Australia and Indonesia can experience drought conditions during El Niño years, while the western United States can experience heavy rainfall.
Monitoring and Prediction
Monitoring and predicting El Niño events are important due to their potential global impacts. Various methods are used to monitor El Niño, including sea surface temperature indices, wind patterns, and changes in sea level pressure known as the Southern Oscillation Index. Predicting El Niño involves complex computer models that simulate the interactions between the ocean and atmosphere.
Conclusion
El Niño is a naturally occurring event in the equatorial region which causes temporary changes in the world climate. It is associated with floods, droughts and other weather disturbances in many regions of the world. However, all the impacts of the El Niño are not negative, in some areas it can bring much needed rain or relief from severe weather.